Re: Fatal error after upgrading to BP 1.1.2
You are welcome.
I am not sure about the fatal error(as it should not appear).
Since the Buddypress menu is available in the admin now,It seems the plugin got activated.
1.rename the wp-content/bp-themes directory to something else[as you upgraded from 1.0.3 which used old theme architecture]
2.copy the themes bp-sn-parent and bp-default from buddypress/bp-themes to wp-content/themes
Go to site back end.Enable the themes and activate the bp-default.hopefully,It will be working.